That’s a short list of other packages (none of which I think are part of a base Linux install, correct me if I’m wrong) that have decided to depend on systemd?
There are multiple libc implementations. libc independence is important and valuable. You'll probably find a "hard dependency on glibc" list in the documentation of e.g. Alpine.
> Or "hard dependency on Bash"?
Ubuntu will have a list from when they switched to ash as /bin/sh. Again, multiple implementations and independence are important, and something the linux community generally cares about.
You could make another SystemD implementation if you really wanted. The point is that there are plenty of APIs - even ones with a single implementation - that nobody bats an eye about programs having a "hard dependency" on, but suddenly for SystemD it's apparently a big issue?
It's bullshit technical excuses to hide the real reasons people object to SystemD, which are more embarrassing.